Supplementary Information
Abnormal drop in electrical resistivity with impurity doping of single-crystal Ag
Ji Young Kim1[+],Min-Wook Oh2[+], Seunghun Lee3[-], Yong Chan Cho4, Jang-Hee Yoon5, Geun Woo Lee6, Chae-Ryong Cho1, Chul Hong Park7*, and Se-Young Jeong3*
1Department of Nano Fusion Technology, Pusan National University, Miryang, 627-706, Republic of Korea
2Fundamental and Creativity Research Division, Korea Electrotechnology Research Institute, Changwon-si, 641-120, Republic of Korea
3Department of Cogno-Mechatronics Engineering, Pusan National University, Miryang, 627-706, Republic of Korea
E-mail:
4Crystal Bank Research Institute, Pusan National University, Miryang 627-706, Republic of Korea
5Busan center, Korea Basic Science Institute, Busan, 618-230, Republic of Korea
6Korea Research Institute of Standards and Science & Department of Science of Measurement, University of Science and Technology, Daejeon, 305-340, Republic of Korea
7Department of Physics Education & RCDAMP, Pusan National University, Busan, 609-735, Republic of Korea
E-mail:
[+] These authors contributed equally to this work.
[*]These authors contributed equally to this work as corresponding authors.
[-] Current address: The Institute of Basic Science, Korea University, Seoul, 136-713, Republic of Korea
Contents of Supplementary Information:
Figures S1-S5
Table S1
Figure S1. a–d: 2.5D XRD plots and e–h: 2D XRD plots of the (111) plane of the Ag–Cu mixed crystals Ag0.99Cu0.01, Ag0.98Cu0.02, Ag0.97Cu0.03, and Ag0.95Cu0.05.
Figure S1 shows the X-ray diffraction (XRD) plots of the (111) plane of the Ag–Cu mixed crystals, with Cu molar fractions in the range of 1–5%, demonstrating that the samples were single crystals. The mixed crystals were grown to exhibit features in the [111] direction, with the main peak slightly off-center. The presence of other smaller peaks suggests the presence of differently oriented domains or twin domains, which typically appear following a cutting process applied to soft metals.
Figure S2. GDS depth profile elemental analyses of the Ag–Cu mixed crystals.
Figure S2 shows the atomic composition of the mixed crystals measured using glow discharge spectrometry (GDS). The measurement was carried out following etching, to remove surface impurities which may have been introduced during wireelectricaldischargemachining (EDM) cutting. Additional impurities (i.e., other than Ag and Cu) are listed in Table S1 for the Ag0.97Cu0.03 sample. The unintentional impurity levels in the Ag0.99Cu0.01, Ag0.98Cu0.02, and Ag0.95Cu0.05 samples were also similar.
Table S1. Atomic composition of unintentional impurities in Ag0.97Cu0.03 at depths of 1, 10, and 50 μm.
Depth[μm] / Co
[%] / Fe
[%] / Mg
[%] / Si
[%] / Ni
[%] / Cr
[%] / P
[%] / S
[%]
1 / 0.000445 / 0.001774 / 0.001038 / 0.005482 / 0.002384 / 0.001593 / 0.001818 / 0.00357
10 / 0.0000502 / 0.000721 / 0.00115 / 0.001377 / 0.001102 / 0.001159 / 0.002745 / 0.001454
50 / 0.000361 / 0.000425 / 0.001412 / 0.000691 / 0.001425 / 0.000769 / 0.001892 / 0.001387
Figure S3. Temperature dependence of the electrical resistivity of the mixed crystals in the temperature range of 100–300 K. The inset shows the temperature dependence of the resistivity of Ag0.97Cu0.03, as compared with that of pure single-crystal Ag.
Figure S3 shows the electrical resistivity of the crystals in the temperature range of 100–300 K. The mixed crystals showed a drop in the resistivity with increasing Cu content in the range of 1–3 mol% and a subsequent rise for the 5 mol% sample. The quality of the mixed crystal Ag0.95Cu0.05 was not worse than that of the other samples. The temperature dependence of the resistivity was reproducible. As shown in the inset, the mixed crystal Ag0.97Cu0.03had alower resistivity than that of thepure single-crystal Ag.
Figure S4. Total energy of the Cu-doped Ag system as a function of the distance between two Cu atoms. The value of the total energy for the Cu–Cu dimer system wasset to zero.
Figure S4 shows the total energy of the Cu-doped Ag system as a function of the distance between two Cu atoms. The ionic positions were relaxed within the constant volume for the total energy calculation.The total energy of the Cu–Cu dimer system, which has the shortest distance, was the lowest value and was set to zero. A solid line from E=k(distance)a, where k and a are fitting parameters, is plotted for guidance.
Figure S5. Density of states for the Cu–Cu dimerized and separatedsystems. The Fermi level of each system wasset to zero.
Figure S5 shows the density of states (DOS) of the Cu–Cu dimerized and separated systems. The difference near the Fermi level is clearly shown. Note that the density of states ranging from about –0.2 to 0.2 eV contributes to carrier transport at room temperature. The difference of the DOS between the two systems, i.e., DOS[Cu–Cu dimer.] –DOS[Cu–Cu separ.],was integrated in the range from–0.2 to 0.2 eV and showedapositive value of ca. 1.7 states, which is attributed to the smaller value of the electrical resistivity ofthe Cu–Cu dimerizedsystem compared withthat ofthe Cu–Cu separated system.